1. Photonics Research Center, University of Malaya; 50603 Kuala Lumpur Malaysia
2. School of Engineering, KDU University College; SS 22/41, Damansara Jaya, 47400 Petaling Jaya Selangor Darul Ehsan Malaysia
3. Department of Electrical Engineering; University of Malaya; 50603 Kuala Lumpur Malaysia